That's what Joaquin Phoenix finds out in Spike Jonze's bittersweet new romantic dramedy, "Her." As outlined in a new trailer, Phoenix plays Theodore Twombly, a writer who's still recovering from a breakup when he gets an intelligent home operating system.

Soon, Theodore's relationship with "Samantha" (the voice of Scarlett Johansson) starts to deepen and evolve. "It's been a long time since I've been with somebody I felt totally at ease with," he says.

As unlikely and odd a man/machine romance may seem, the brief scenes in the trailer are heartwarming and touching. And as his friend (Amy Adams) notes, "Falling in love is a crazy thing to do. It's kind of like a form of socially acceptable insanity."